Large, bulky loads, such as a stack of sheet rock, a piano or other similar items, often are difficult to carry into buildings and transfer to the desired floor level. At construction sites having buildings with large, elevated openings, and in other environments, such as a warehouse which includes different levels of floors and platforms, heavy and bulky objects are more easily transferred by crane to a work-in-storage position adjacent the desired level and then carried onto the floor.
Various apparatus have been designed for transferring a load of material to a work-in-storage position and then unloading the material onto a floor such as in an elevated building opening. One apparatus includes a forklift on an assembly mounted to a building crane. Another apparatus includes separate means having a hoist and moveable support. One apparatus, designed especially for use at a construction site for the unloading of bulk building materials such as a stack of sheet rock into an elevated building opening, is disclosed in U.S. Pat. No. 3,827,744 to Ferdelman et al. This apparatus includes a platform having platform support extensions protruding forwardly therefrom for engaging the floor edge of an elevated building opening. An unloading ramp secured to the platform pivots downwardly from a vertical position to a horizontal position to provide a bridge between the platform and the building floor edge for permitting personnel or a forklift machine to enter onto the platform and remove the material therefrom.
However, the aforementioned apparatus disclosed in Ferdelman et al poses safety limitations. Men and machinery must enter onto the platform to remove the material therefrom. Because a crane holds the platform in an elevated position, minor crane movements or wind shifts may cause the platform to veer from the building causing a man to stumble and fall.